Develop Reference

ImageReader.OnImageAvailableListener() not being called when taking a picture

I have a Camera App developed for Android 26 SDK. I have been using it happily with a Motorola G5 and G6 but when I move to a Motorola G7 the app crashes when I press the button to take a picture in my app.
The G7 is running Android 9. I have another Android 9 phone a Samsung S10 plus. The S10 plus does not crash when I press the button for taking a picture.
While debugging I noticed that the G7 doesn't call ImageReader.OnImageAvailableListener while the S10 does. Looking at the code this is where the image is saved for use later on in CameraCaptureSession.CaptureCallback. The callback expects bytes to be populated and crashes when it isn't (I haven't included the stack trace because it's not a little unhelpful but I can if you think you would like to see it).
I can get the G7 to save the image if I run it slowly through debug on 'some' occasions.
So I have a button that calls the function onImageCaptureClick() inside it does a bunch of stuff but one of the things it does is create an ImageReader.OnImageAvailableListener. The OnImageAvailableListener saves the image and populates a variable bytes from the image buffer. This onImageAvailableListener is attached to my reader by using reader.setOnImageAvailableListener(readerListener, null), and this listener is never used. When I get in to the CaptureCallBack the class variable bytes is not populated and the app crashes.
Do you have any idea where I would look to solve this?
protected void onImageCaptureClick() {
if (null == mCameraDevice) {
logger.debug("null == mCameraDevice");
Log.e(TAG, "cameraDevice is null");
return;
}
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
CameraCharacteristics characteristics = manager.getCameraCharacteristics(mCameraDevice.getId());
Size[] jpegSizes = null;
if (characteristics != null) {
jpegSizes = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(ImageFormat.JPEG);
}
int width = 640;
int height = 480;
if (jpegSizes != null && 0 < jpegSizes.length) {
width = jpegSizes[0].getWidth();
height = jpegSizes[0].getHeight();
}
ImageReader reader = ImageReader.newInstance(width, height, ImageFormat.JPEG, 1);
List < Surface > outputSurfaces = new ArrayList < > (2);
outputSurfaces.add(reader.getSurface());
outputSurfaces.add(new Surface(mTextureView.getSurfaceTexture()));
final CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(reader.getSurface());
if (mFlashMode == FLASH_MODE_OFF) {
captureBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
logger.debug("FLASH OFF");
}
if (mFlashMode == CONTROL_AE_MODE_ON) {
captureBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON);
captureBuilder.set(CaptureRequest.FLASH_MODE,
CaptureRequest.FLASH_MODE_TORCH);
logger.debug("FLASH ON");
}
if (mFlashMode == CONTROL_AE_MODE_ON_AUTO_FLASH) {
captureBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
captureBuilder.set(CaptureRequest.FLASH_MODE,
CaptureRequest.FLASH_MODE_OFF);
logger.debug("FLASH AUTO");
}
captureBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
int rotation = getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
final File file = new File(_pictureUri.getPath());
logger.debug("OnImageCaptureClick: _pictureUri is: " + _pictureUri.getPath());
// ************************************
// this listener is not used on the G7,
// and so the image isn't saved.
// ************************************
ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
#Override
public void onImageAvailable(ImageReader reader) {
Image image = null;
try {
image = reader.acquireLatestImage();
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
bytes = new byte[buffer.capacity()];
buffer.get(bytes);
logger.debug("onImageCaptureClick, the filesize to save is: " + bytes.toString());
save();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (image != null) {
image.close();
}
}
}
private void save() throws IOException {
OutputStream output = null;
try {
output = new FileOutputStream(file);
output.write(bytes);
} finally {
if (null != output) {
output.close();
}
}
}
};
// ********************************************************
// the reader sets the listener here but it is never called
// and when I get in to the CaptureCallback the BitmapUtils
// expects bytes to be populated and crashes the app
// ********************************************************
reader.setOnImageAvailableListener(readerListener, null);
final CameraCaptureSession.CaptureCallback captureListener = new CameraCaptureSession.CaptureCallback() {
#Override
public void onCaptureCompleted(#NonNull CameraCaptureSession session, #NonNull CaptureRequest request, #NonNull TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
try {
BitmapUtils.addTimeStampAndRotate(_pictureUri, bytes);
Intent intent = new Intent(CameraActivity.this, CameraReviewPhotoActivity.class);
intent.putExtra(MediaStore.EXTRA_OUTPUT, _pictureUri);
startActivityForResult(intent, CameraActivity.kRequest_Code_Approve_Image);
} catch (IOException e) {
e.printStackTrace();
} catch (ImageReadException e) {
e.printStackTrace();
} catch (ImageWriteException e) {
e.printStackTrace();
}
}
};
mCameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {
#Override
public void onConfigured(CameraCaptureSession session) {
try {
session.capture(captureBuilder.build(), captureListener, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
#Override
public void onConfigureFailed(CameraCaptureSession session) {
Log.w(TAG, "Failed to configure camera");
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
} finally {
takePictureButton.setEnabled(false);
mTextureView.setEnabled(false);
}

The API makes no guarantee about the order of onCaptureCompleted and OnImageAvailableListener. They may arrive in arbitrary order, depending on the device, capture settings, the load on the device, or even the particular OS build you have.
Please don't make any assumptions about it.
Instead, if you need both callbacks to fire before you process something, then wait for both to happen before you move forward. For example, check if the other callback has fired in each callback, and if so, call the method to do the processing.

I think I have found the solution to this.
I have the following phones:
Samsung S10 Plus
Motorola G7
Motorola G6
My app works on the S10 and the G6.
The S10 and G6 both call the OnImageAvailableListener function before the onCaptureCompleted callback. The G7 however calls them both the other way around onCaptureCompleted then OnImageAvailableListener.
According to https://proandroiddev.com/understanding-camera2-api-from-callbacks-part-1-5d348de65950 the correct way is onCaptureCompleted then OnImageAvailableListener.
In my code I am assuming that OnImageAvailableListener has saved the image and then OnCaptureCompleted tries to manipulate it, which causes the crash.
Looking at the INFO_SUPPORTED_HARDWARE_LEVEL of each device I have the following levels of support from none level 0 to uber level 3.
Samsung S10 Plus reports device level support level 1
Motorola G7 reports device level support level 3
Motorola G6 reports device level support level 2
My assumption at this point is that the events fire in a different order when you support the android-camera2 API at Level 3 compared to other levels.
Hope this helps

MediaCodec's Persistent Input Surface unsupported by Camera2 Session?

I am writing an Android app that supports saving RAW/JPEG and records videos at the same time. I tried passing 4 surfaces when creating CameraCaptureSession: preview, 2x ImageSaver and 1x PersistentInputSurface created by MediaCodec#createPersistentInputSurface. By using persistent input surface, I intend to avoid a stoppage between 2 captures.
When creating the session it fails with:
W/CameraDevice-JV-0: Stream configuration failed due to: endConfigure:380: Camera 0: Unsupported set of inputs/outputs provided
Session 0: Failed to create capture session; configuration failed
I have tried taking out all other surfaces, leaving only the PersistentInputSurface, still fails.
#Override
public void onResume() {
super.onResume();
//Some other setups...
if (persistentRecorderSurface == null) {
persistentRecorderSurface = MediaCodec.createPersistentInputSurface();
}
startBackgroundThread();
startCamera();
if (mPreviewView.isAvailable()) {
configureTransform(mPreviewView.getWidth(), mPreviewView.getHeight());
} else {
mPreviewView.setSurfaceTextureListener(mSurfaceTextureListener);
}
if (mOrientationListener != null && mOrientationListener.canDetectOrientation()) {
mOrientationListener.enable();
}
}
private void createCameraPreviewSessionLocked() {
try {
SurfaceTexture texture = mPreviewView.getSurfaceTexture();
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface surface = new Surface(texture);
mPreviewRequestBuilder = mBackCameraDevice.createCaptureRequest(
CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
mBackCameraDevice.createCaptureSession(Arrays.asList(
surface,
mJpegImageReader.get().getSurface(),
mRAWImageReader.get().getSurface(),
persistentRecorderSurface
), new CameraCaptureSession.StateCallback() {
#Override
public void onConfigured(CameraCaptureSession session) {
synchronized (mCameraStateLock) {
if (mBackCameraDevice == null) {
return;
}
try {
setup3AControlsLocked(mPreviewRequestBuilder);
session.setRepeatingRequest(mPreviewRequestBuilder.build(),
mPreCaptureCallback, mBackgroundHandler);
mState = CameraStates.PREVIEW;
} catch (CameraAccessException | IllegalStateException e) {
e.printStackTrace();
return;
}
mSession = session;
}
}
#Override
public void onConfigureFailed(CameraCaptureSession session) {
showToast("Failed to configure camera.");
}
}, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}

It'd be helpful to see the system log lines right before that error line to confirm, but most likely:
You need to actually tie the persistentRecorderSurface to a MediaRecorder or MediaCodec, and call prepare() on those, before you create the camera capture session.
Otherwise, there's nothing actually at the other end of the persistent surface, and the camera can't tell what resolution or other settings are required.
Also keep in mind that there are limits on how many concurrent outputs you can have from the camera, depending on its supported hardware level and capabilities. There is currently no requirement that a device must support your combination of outputs (preview, record, JPEG, RAW), unfortunately, so it's very likely many or all devices will still give you an error.

surface for openCV with Android: already connected

I'm trying to connect my Android app with the OpenCV library and I need to use a native camera for have more control of the camera options. For do it I have found http://nezarobot.blogspot.it/2016/03/android-surfacetexture-camera2-opencv.html, that is what I need.
My problem is that if I use this code, with some small change and when I launch it, my app crash with 3 errors reported:
E/BufferQueueProducer: [SurfaceTexture-0-31525-0] connect(P): already connected (cur=4 req=2)
D/PlateNumberDetection/DetectionBasedTracker: ANativeWindow_lock failed with error code -22
A/libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x315e9858 in tid 31735 (CameraBackgroun)
I have tried to close the camera before the jni call and I can capture and show only the first frame, but then I need to restart the camera and I can't create the same thread by itself.
Here I take the frame and I send to NDK.
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
= new ImageReader.OnImageAvailableListener() {
#Override
public void onImageAvailable(ImageReader reader) {
Image image;
try {
image = reader.acquireLatestImage();
if( image == null) {
return;
}
if (image.getFormat() != ImageFormat.YUV_420_888) {
throw new IllegalArgumentException("image must have format YUV_420_888.");
}
Image.Plane[] planes = image.getPlanes();
if (planes[1].getPixelStride() != 1 && planes[1].getPixelStride() != 2) {
throw new IllegalArgumentException(
"src chroma plane must have a pixel stride of 1 or 2: got "
+ planes[1].getPixelStride());
}
mNativeDetector.detect(image.getWidth(), image.getHeight(), planes[0].getBuffer(), surface);
} catch (IllegalStateException e) {
Log.e(TAG, "Too many images queued for saving, dropping image for request: ", e);
return;
}
image.close();
}
};
and here I manage the camera preview
protected void createCameraPreview() {
try {
SurfaceTexture texture = textureView.getSurfaceTexture();
assert texture != null;
texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
surface = new Surface(texture);
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
captureRequestBuilder.addTarget(mImageReader.get().getSurface());
BlockingSessionCallback sessionCallback = new BlockingSessionCallback();
List<Surface> outputSurfaces = new ArrayList<>();
outputSurfaces.add(mImageReader.get().getSurface());
outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
cameraDevice.createCaptureSession(outputSurfaces, sessionCallback, mBackgroundHandler);
try {
Log.d(TAG, "waiting on session.");
cameraCaptureSessions = sessionCallback.waitAndGetSession(SESSION_WAIT_TIMEOUT_MS);
try {
captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CaptureRequest.CONTROL_MODE_AUTO);
Log.d(TAG, "setting repeating request");
cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(),
mCaptureCallback, mBackgrounHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
} catch (TimeoutRuntimeException e) {
Toast.makeText(AydaMainActivity.this, "Failed to configure capture session.", Toast.LENGTH_SHORT);
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
}

Have you tried that code without your "some small change" first? I have tried that project and it worked well on multiple devices. So it will be useful to first establish if it does not work on your phone at all, or if there is a problem in your modifications.

Android Camera2, take picture continuously

I need to take pictures continuously with Camera2 API. It works fine on high end devices (for instance a Nexus 5X), but on slower ones (for instance a Samsung Galaxy A3), the preview freezes.
The code is a bit long, so I post only the most relevant parts:
Method called to start my preview:
private void startPreview() {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
if(texture != null) {
try {
// We configure the size of default buffer to be the size of camera preview we want.
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// This is the output Surface we need to start preview.
Surface surface = new Surface(texture);
// We set up a CaptureRequest.Builder with the output Surface.
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// Here, we create a CameraCaptureSession for camera preview.
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()), new CameraCaptureSession.StateCallback() {
#Override
public void onConfigured(#NonNull CameraCaptureSession cameraCaptureSession) {
// If the camera is already closed, return:
if (mCameraDevice == null) { return; }
// When the session is ready, we start displaying the preview.
mCaptureSession = cameraCaptureSession;
// Auto focus should be continuous for camera preview.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
mPreviewRequest = mPreviewRequestBuilder.build();
// Start the preview
try { mCaptureSession.setRepeatingRequest(mPreviewRequest, null, mPreviewBackgroundHandler); }
catch (CameraAccessException e) { e.printStackTrace(); }
}
#Override
public void onConfigureFailed(#NonNull CameraCaptureSession cameraCaptureSession) {
Log.e(TAG, "Configure failed");
}
}, null
);
}
catch (CameraAccessException e) { e.printStackTrace(); }
}
}
Method called to take a picture:
private void takePicture() {
try {
CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
mCaptureSession.capture(captureBuilder.build(), null, mCaptureBackgroundHandler);
}
catch (CameraAccessException e) { e.printStackTrace(); }
}
And here is my ImageReader:
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
#Override
public void onImageAvailable(final ImageReader reader) {
mSaveBackgroundHandler.post(new Runnable() {
#Override
public void run() {
// Set the destination file:
File destination = new File(getExternalFilesDir(null), "image_" + mNumberOfImages + ".jpg");
mNumberOfImages++;
// Acquire the latest image:
Image image = reader.acquireLatestImage();
// Save the image:
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(destination);
output.write(bytes);
}
catch (IOException e) { e.printStackTrace(); }
finally {
image.close();
if (null != output) {
try { output.close(); }
catch (IOException e) { e.printStackTrace(); }
}
}
// Take a new picture if needed:
if(mIsTakingPictures) {
takePicture();
}
}
});
}
};
I have a button that toggle the mIsTakingPictures boolean, and makes the first takePicture call.
To recap, I'm using 3 threads:
one for the preview
one for the capture
one for the image saving
What can be the cause of this freeze?

It's impossible to avoid framing lost in your preview when you are taking images all time on weak devices. The only way to avoid this is on devices which support TEMPLATE_ZERO_SHUTTER_LAG and using a reprocessableCaptureSession. The documentation about this is pretty horrible and find a way to implement it can be a odyssey. I have this problem a few months ago and finally I found the way to implement it:
How to use a reprocessCaptureRequest with camera2 API
In that answer you can also find some Google CTS test's which also implements ReprocessableCaptureSession and shoot some burst captures with ZSL template.
Finally, you can also use a CaptureBuilder with your preview surface and the image reader surface attached, in that case your preview will continue working all time and also you will save each frame as a new picture. But you will still having the freeze problem.
I also tried implement a burst capture using a handler which dispatch a new capture call each 100 milliseconds, this second option was pretty good in performance and avoiding frame rate lost, but you will not get as many captures per second like the two ImageReader option.
Hope that my answer will help you a bit, API 2 still being a bit complex and there's not so many examples or information about it.

One thing I noticed on low end devices: the preview stops after a capture, even when using camera 1 api, so it has to be restarted manually, thus producing a small preview freeze when capturing a high resolution picture.
But the camera 2 api provides the possibility to get raw image when taking a still capture (that wasn't possible on the devices I have when using camera 1 (Huawei P7, Sony Xperia E5, wiko UFeel)). Using this feature is much faster than capturing a JPEG (maybe due to JPEG compression), so the preview can be restarted earlier, and the preview freeze is shorter. Of course using this solution you'll have to convert the picture from YUV to JPEG in a background task..

How to get each frame data using camera2 API in Android5.0 in realtime

I am working with camera2Basic now and trying to get each frame data to do some image processing. I am using camera2 API in Android5.0, everything is fine when only doing the camera preview and it is fluid. But the preview stuck when I use the ImageReader.OnImageAvailableListener callback to get each frame data, this cause a bad User Experience.
The following is my related codes:
This is the setup for camera and ImageReader, I set the format of image is YUV_420_888
public<T> Size setUpCameraOutputs(CameraManager cameraManager,Class<T> kClass, int width, int height) {
boolean flagSuccess = true;
try {
for (String cameraId : cameraManager.getCameraIdList()) {
CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
// choose the front or back camera
if (FLAG_CAMERA.BACK_CAMERA == mChosenCamera &&
CameraCharacteristics.LENS_FACING_BACK != characteristics.get(CameraCharacteristics.LENS_FACING)) {
continue;
}
if (FLAG_CAMERA.FRONT_CAMERA == mChosenCamera &&
CameraCharacteristics.LENS_FACING_FRONT != characteristics.get(CameraCharacteristics.LENS_FACING)) {
continue;
}
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
Size largestSize = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.YUV_420_888)),
new CompareSizesByArea());
mImageReader = ImageReader.newInstance(largestSize.getWidth(), largestSize.getHeight(),
ImageFormat.YUV_420_888, 3);
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mBackgroundHandler);
...
mCameraId = cameraId;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
}
......
}
When the camera opened successfully, I Create a CameraCaptureSession for camera preview
private void createCameraPreviewSession() {
if (null == mTexture) {
return;
}
// We configure the size of default buffer to be the size of camera preview we want.
mTexture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// This is the output Surface we need to start preview
Surface surface = new Surface(mTexture);
// We set up a CaptureRequest.Builder with the output Surface.
try {
mPreviewRequestBuilder =
mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(mImageReader.getSurface());
mPreviewRequestBuilder.addTarget(surface);
// We create a CameraCaptureSession for camera preview
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
#Override
public void onConfigured(CameraCaptureSession session) {
if (null == mCameraDevice) {
return;
}
// when the session is ready, we start displaying the preview
mCaptureSession = session;
// Finally, we start displaying the camera preview
mPreviewRequest = mPreviewRequestBuilder.build();
try {
mCaptureSession.setRepeatingRequest(mPreviewRequest,
mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
#Override
public void onConfigureFailed(CameraCaptureSession session) {
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
The last is the ImageReader.OnImageAvailableListener callback
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
#Override
public void onImageAvailable(ImageReader reader) {
Log.d(TAG, "The onImageAvailable thread id: " + Thread.currentThread().getId());
Image readImage = reader.acquireLatestImage();
readImage.close();
}
};
Maybe I do the wrong setup but I try several times and it doesn't work. Maybe there is another way to get frame data rather than ImageReader but I don't know.
Anybody knows how to get each frame data in realtime?

I do not believe that Chen is correct. The image format has almost 0 effect on the speed on the devices I have tested. Instead, the problem seems to be with the image size. On an Xperia Z3 Compact with the image format YUV_420_888, I am offered a bunch of different options in the StreamConfigurationMap's getOutputSizes method:
[1600x1200, 1280x720, 960x720, 720x480, 640x480, 480x320, 320x240, 176x144]
For these respective sizes, the maximum fps I get when setting mImageReader.getSurface() as a target for the mPreviewRequestBuilder are:
[13, 18, 25, 28, 30, 30, 30, 30 ]
So one solution is to use a lower resolution to achieve the rate you want. For the curious... note that these timings do not seem to be affected by the line
mPreviewRequestBuilder.addTarget(surface);
...
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
I was worried that adding the surface on the screen might be adding overhead, but if I remove that first line and change the second to
mCameraDevice.createCaptureSession(Arrays.asList(mImageReader.getSurface()),
then I see the timings change by less than 1 fps. So it doesn't seem to matter whether you are also displaying the image on the screen.
I think there is simply some overhead in the camera2 API or ImageReader's framework that makes it impossible to get the full rate that the TextureView is clearly getting.
One of the most disappointing things of all is that, if you switch back to the deprecated Camera API, you can easily get 30 fps by setting up a PreviewCallback via the Camera.setPreviewCallbackWithBuffer method. With that method, I am able to get 30fps regardless of the resolution. Specifically, although it does not offer me 1600x1200 directly, it does offer 1920x1080, and even that is 30fps.

I'm trying the same things, I think you may change the Format like
mImageReader = ImageReader.newInstance(largestSize.getWidth(),
largestSize.getHeight(),
ImageFormat.FLEX_RGB_888, 3);
Because using the YUV may cause CPU to compress the data and it may cost some time. RGB can be directly showed on the device. And detect face from image should put in other Thread you must know it.